The present invention relates to a method and composition for determining contaminants in fats and oils. More specifically, the present invention relates to an easy to use, inexpensive method and composition to evaluate the quality of fats and oils, especially as regards soap and other alkaline substance levels.
One of the factors determining the cooking quality of used frying fats and oils is the amount of alkaline substances, including soaps, initially present and accumulated in the fat or oil during cooking. Normally, the more alkaline substances in the fat or oil, the worse the cooking properties of the fat or oil. However, for a restaurant or a fast-food outlet, it is difficult to evaluate the quality of the used cooking oil on the premises, other than by merely looking at its color, smelling its odor, and/or observing its frying properties.
The American Oil Chemists' Society (A.O.C.S.) has set up certain standard methods for evaluating the quality of freshly refined cooking oil, including the amount of "soaps" in the fresh oil. Presently, the amount of soaps in freshly refined fat and oil is determined by procedures which are both relatively complex and require substantial apparatus and a trained operator. For example, the A.O.C.S. Recommended Practice Cc 17-79 requires a titration to determine the amount of soaps in the fresh oil. Accordingly, this method requires equipment and solutions not normally found in restaurants and fast-food outlets. Moreover, the procedure is not recommended for use with used cooking oils.
Others have developed standard methods for determining the quality characteristics of used cooking oils by determining, among other things, free fatty acid content, color, odor, etc. However, while the amounts of alkaline substances in used cooking oil have previously been determined, until recently, there has not been any real interest in measuring the amount of "soaps" in used cooking oil either on the industrial level or on the restaurant or fast-food outlet level, since "soaps" were not considered important in determining the quality of the oil. In addition, such facilities did not have the apparatus required to make such determinations. Moreover, as far as applicants know, no one has developed standards or test procedures for determining the quality characteristics of used cooking oils in terms of the alkaline substances therein, including soaps. As is pointed out in U.S. application Ser. No. 069,238 filed Aug. 23, 1979 of Bernard Friedman, such alkaline substances have been found to contribute to the loss of desirable cooking properties in the used cooking oil. Thus, it would be very desirable to have a quick, easy and inexpensive way to measure the amounts of such alkaline substances in used cooking oil.
The present applicants have found in performing the above-mentioned A.O.C.S. Recommended Method that when higher levels of alkaline substances are present as in used fats, the recommended procedure has a number of disadvantages. Two such disadvantages are (1) the formation of emulsions, and (2) lack of correlation of known high amounts of soaps in fats (prepared by adding known amounts of soaps to soap-free fats) and the results found for such fats by the Recommended Method. Also, the method is specifically recommended for vegetable oils.
Thus, it would also be desirable to provide a method by which soap levels in various types of fats could be determined regardless of their origin and by which higher levels of soap concentrations can be more accurately measured, which high levels correlate to a fry chef's judgment of when a fat or oil is no longer suitable for frying.